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mnowicki
05-20-2007, 06:01 PM
Does anyone know the specs of the decibel meter they use at the detroit comp, or which model in particular? If not does anyone have recommendations of which one to buy because we had trouble passing noise this year. Thanks.
mnowicki
05-20-2007, 06:01 PM
Does anyone know the specs of the decibel meter they use at the detroit comp, or which model in particular? If not does anyone have recommendations of which one to buy because we had trouble passing noise this year. Thanks.
ach1
05-20-2007, 06:21 PM
We use a Radio Shack model 33-2055. $50.00
And it gave the same dB as the official meter at competition. They use a Bruel & Kjaer, unsure of the model and considerably more expensive. E-mail gary.newton@bksv.com if you really need to know the model they use.

http://www.radioshack.com/product/index.jsp?productId=2...er&parentPage=search (http://www.radioshack.com/product/index.jsp?productId=2103667&cp=&sr=1&origkw=sound+meter&kw=sound+meter&parentPage=search)
Kurt Bilinski
05-20-2007, 07:12 PM
To the OP, make sure to use an identical physical setup as is used at competition, else it won't give the same results.
BStoney
05-20-2007, 07:23 PM
Notably, they finally mounted the microphone on a boom stand style setup so that repeatability in measurements was very very good this year. Surely had something to do with the fact that only 40 or so teams got through sound on the first day this year...
Tech Guy
05-21-2007, 09:36 AM
As one who was formerly responsible for the noise testing and development for trucks for one of the OEM's, and formerly Sound Control Chief for the local SCCA region, a couple of thoughts about noise testing:
1. It is not much use having a sound level meter unless you also have a calibrator, and using it while you are doing the testing. Without it, the meter could be "off" by several dB.
2. Teams that try and "develop" their exhaust system to get as close as possible to the 110 dBA limit are going to get caught out a lot of the time. Noise is ambient condition dependent, AND there are no correction factors. So a wise team will calibrate their meter AND aim to have a 3-4 dBA margin, i.e. come in at 106-107 dBA.

The FSAE noise test is simple and repeatable. So there is no real excuse for a team going to a competition and failing the noise test.